MDS PREP
What does ORMOCER stand for in dental materials?
1) Organically Modified Resin Monomer Ceramic
2) Organically Modified Resin Matrix Composite
3) Organically Modified Ceramic Resin
4) Ormocer is not an acronym.
ORMOCER stands for Organically Modified Ceramic, which is a type of advanced filling material that combines the properties of ceramics and resins for superior performance in dental restorations.
What is the primary reason for using zinc polycarboxylate cement as a luting agent?
1) Its high compressive strength
2) Its ability to bond chemically to tooth structure
3) Its ease of manipulation
4) Its insolubility in oral fluids
Zinc polycarboxylate cement is favored as a luting agent for its chemical bonding capability with tooth structure.
What is the significance of the hybrid layer in dentin bonding?
1) It provides a barrier to prevent microleakage.
2) It has no significant role in bond strength.
3) It improves the aesthetics of the restoration.
4) It is an artifact of the etching process.
The hybrid layer formed by the infiltration of resin into the etched dentin provides a strong mechanical interlock and acts as a barrier to prevent microleakage between the restoration and the tooth structure.
What are Compomers more correctly termed?
1) Methacryloxy decyl pyridinium bromide-modified composite resins
2) Polyacid-modified composite resins
3) Polymethacrylate-based composite resins
4) Glass ionomer-modified composite resins
Compomers are more correctly termed Polyacrylic acid Modified Composite Resins (PMCRs). They are a blend of glass ionomer and composite resin properties, making them user-friendly and suitable for certain restorative procedures.
What is the ADA specification for the gelation temperature of agar-agar hydrocolloids?
1) It should not be less than 32°C
2) It should be exactly 32°C
3) It should be more than 32°C
4) There is no specific ADA specification for gelation temperature
The American Dental Association (ADA) Specification-11 states that the gelation temperature should not be less than 32°C to ensure proper setting and avoid distortion of the impression.
What is the pH of zinc polycarboxylate cement after 28 days?
1) 2.8
2) 3.7
3) 5.2
4) 5.8
The pH values provided in the text indicate that zinc polycarboxylate cement reaches a pH of 5.8 after 28 days.
What is the effect of adding potassium sulfate to gypsum-based materials?
1) It accelerates the setting reaction.
2) It retards the setting reaction.
3) It increases the porosity.
4) It has no effect on the setting reaction.
Potassium sulfate acts as an accelerator by increasing the solubility of the hemihydrate and promoting the formation of dihydrate, which speeds up the setting process.
How many grams of high-density noble metal alloy is required for casting of a molar?
1) 3 gms
2) 6 gms
3) 9 gms
4) 12 gms
Dental Materials Answer: 3
With high-density noble metal alloy 6 grams is adequate for premolar and anterior castings, 9 grams is adequate for molar casting and 12 grams is adequate for pontics.